The advent of computer-aided design ("CAD") tools capable of digitally representing and rendering three-dimensional objects has engendered efforts to automatically fabricate, based on these representations, replicas of the objects themselves. Three-dimensional modeling systems are particularly useful in prototyping applications, e.g., construction of proposed mechanical parts for the purpose of testing fit and appearance. Rapid prototyping alleviates the need for sophisticated machining or the preparation of molds to form preliminary models that may well be discarded.
Unfortunately, current approaches to automatic model fabrication tend to be cumbersome, expensive and vulnerable to malfunction. For example, available systems frequently employ solid material that is heated and extruded into a flowable state, then exposed to energy that solidifies the material upon deposition; see, e.g., U.S. Pat. Nos. 5,134,569, 5,506,607 and 5,348,604. The need for a continuous supply of fluent material requires specialized heating equipment and conduits that may clog; and the need to resolidify the material using directed energy imposes further equipment demands. Moreover, the need to cure each droplet as it is deposited may restrict the speed of operation.
Other approaches utilize selective sintering or coalescence of a powdered solid; see, e.g., U.S. Pat. Nos. 5,182,170 and 5,354,414. These systems require special containment to handle and minimize loss to the environment of fine granular material, as well as complex equipment and operations.
Some approaches in the prior art utilize lasers in connection with extrusion systems (U.S. Pat. No. 5,208,431), stereolithography (U.S. Pat. No. 5,130,064) or to alter solubility characteristics (U.S. Pat. No. 5,183,598). Again, these systems tend to be complex and cumbersome, utilizing relatively exotic application materials and equipment.